package MyLinkedList;

public class MyLinkedList implements IList{

    static class ListNode{
        public int val;
        public ListNode next;
        public ListNode prev;

        public ListNode(int val) {
            this.val = val;
        }
    }

    public ListNode head;
    public ListNode last;
    
    @Override
    public void addFirst(int data) {
        ListNode node = new ListNode(data);
        if (head == null){
            head = last = node;
        }else {
            node.next = head;
            head.prev = node;
            head = node;
        }

    }

    @Override
    public void addLast(int data) {

        ListNode node = new ListNode(data);
        if (head == null){
            head = last = node;
        }else {
            last.next = node;
            node.prev = last;
            last = last.next;
        }
    }

    protected void checkIndex(int index) throws IndexIllegal{
        int len = size();
        if (index > len || index < 0){
            throw new IndexIllegal("index位置不合法！");
        }
    }
    @Override
    public void addIndex(int index, int data) {
        int len = size();
        checkIndex(index);
        if (index == 0){
            addFirst(data);
            return;
        }
        if (index == len){
            addLast(data);
            return;
        }
        ListNode node = new ListNode(data);
        ListNode cur = head;
        while(index != 0){
            cur = cur.next;
            index--;
        }
        node.next = cur;
        cur.prev.next = node;
        node.prev = cur.prev;
        cur.prev = node;
    }

    @Override
    public boolean contains(int key) {
        ListNode cur = head;
        while (cur != null){
            if(cur.val == key){
                return true;
            }
            cur = cur.next;
        }
        return false;
    }

    @Override
    public void remove(int key) {
        ListNode cur = head;
        while(cur != null){
            if (cur.val == key){
                if (cur == head){//判断头节点
                    head = head.next;
                    if (head != null) {//判断是否是仅有一个节点，那么前驱域prev与后驱域next都是空的，若此时再置空就会出现空指针异常
                        head.prev = null;

                    }
                }else {
                    cur.prev.next = cur.next;//前驱的后驱引用连接目标节点的下一个地址  这是一个公用部分
                    if (cur.next == null) {//判断是不是尾节点
                        last = last.next;//将其尾部节点的引用置空
                    }else {
                        //中间节点部分：
                        cur.next.prev = cur.prev;
                    }
                }
                return;
            }
            cur = cur.next;
        }
    }

    @Override
    public void removeAllKey(int key) {
        ListNode cur = head;
        while(cur != null){
            if (cur.val == key){
                if (cur == head){//判断头节点
                    head = head.next;
                    if (head != null) {//判断是否是仅有一个节点，那么如果是，则前驱域prev与后驱域next都是空的，若此时再置空就会出现空指针异常
                        head.prev = null;
                    }
                }else {
                    cur.prev.next = cur.next;//前驱的后驱引用连接目标节点的下一个地址  这是一个公用部分
                    if (cur.next == null) {//判断是不是尾节点
                        last = last.next;//将其尾部节点的引用置空
                    }else {
                        //中间节点部分：
                        cur.next.prev = cur.prev;
                    }
                }
            }
            cur = cur.next;
        }
    }


    @Override
    public int size() {
        int count = 0;
        ListNode cur = head;
        while(cur != null){
            count++;
            cur = cur.next;
        }
        return count;
    }

    @Override
    public void clear() {
        ListNode cur = head;
        while (cur != null){
            ListNode curN = cur.next;
             cur.prev = null;
             cur.next = null;
             cur = curN;
             //先遍历，把中间节点都去置空，但是head，last并未置空，会一直引用，所以再单独置空
        }
        //所以再单独置空
        head = null;
        last = null;
    }

    @Override
    public void display() {
        ListNode cur = head;
        while(cur != null){
            System.out.print(cur.val + " ");
            cur = cur.next;
        }
        System.out.println();
    }
}
